The present invention relates to exercise equipment of the type having a cable, the proximal end of which is attached to a device, such as a handle, that is pulled or pushed by a user against a restraining force imparted by a resistance device that is coupled to the cable's distal end. Exercise equipment of this type is well known and is disclosed, for example, in my U.S. Pat. Nos. 5,102,122 and 6,705,976, both of which are incorporated herein by reference.
As used herein, the term “cable” is intended to mean and include any elongate flexible member, such as a steel cable, plastic coated steel cable, stranded rope, flexible wire, or a strap or strip made of plastic, leather or rubber. The cable has “proximal” or near end, to which the user applies a force, and a “distal” or remote end attached to a resistance device. The device attached to the proximal end that is pushed or pulled by a user may, for example, be a handle that is grasped by the user's hand, a pad that is pressed by the user's body or a strap that is tied around the user's waist and pulled by the user.
The resistance device is normally a weight stack; that is, a stack of weights which are mounted to slide vertically on one or more guide rails. The distal end of the cable is coupled to a device that may be connected to one or more weights to allow the user to select the number of weights to be lifted when pulling or pushing the handle. The resistance force applied by the weights is substantially constant, independent of the height that the weights are lifted, but their substantial inertia applies a strong acceleration-dependent tensile force to the cable.
Other types of resistance devices, which may be used alone or in combination with a weight stack, are disclosed in my co-pending patent applications Ser. Nos. 09/965,032 and 10/736,807, referenced above. These include one or more elastic bands or springs, coupled to the distal end of the cable, to apply a distance-dependent tensile force to the cable. In addition, or in the alternative, the resistance device may include one or more damping devices coupled to the distal end of the cable to apply a speed-dependent tensile force to the cable.
Various systems are known for monitoring and recording the user's performance in an exercise machine. The U.S. Pat. No. 6,669,600 discloses a system for collecting work and power performance data on any type of exercise equipment. This system remotely senses movements of the limb of a person's body, such as an arm or leg, and records them with a time stamp. Movements of the limb are detected by a magnetic sensor, attached to the exercise equipment, which senses motions of small magnet on the limb. The sensor signals are digitized and supplied to a computer for analysis. If a weight stack machine is used, the weight and distance of travel must be entered separately into the computer, e.g., by a keyboard.
Several devices are known which can automatically determine the number of weights selected in an exercise machine having a weight stack. These are disclosed, for example, in the U.S. Pat. Nos. 5,785,632 and 6,358,188 and in the U.S. Patent Publication No. 2003/0211916. These systems are equipped with special purpose devices, such as a bar code reader or the like, which determines the number of weights which have been selected.
The U.S. Patent Publication 2003/0069108 discloses a monitoring system for a weight stack-type exercise machine which counts the number of times that weights are lifted within a prescribed period of time. The number of weights lifted can be entered into the device by means of a keypad.
The U.S. Pat. No. 5,800,310 discloses a machine for measuring the force exerted by the user's muscles and displaying the strength of the muscles at different positions of the user's body part. In order to measure the static strength of a user's lumbar muscles, the machine utilizes a strain gauge connected between a movement arm and the frame of the machine. Forces applied to the strain gauge are converted into an electric signal which is digitized and stored in a digital computer.
While this exercise equipment does utilize a cable coupled at its distal end to a weight stack, it is designed for very small movements which can be measured by the compression applied to the strain gauge.
None of the exercise machines disclosed in this prior art provide means for monitoring and recording the tension in a cable that is provided by the resistance device coupled to the distal end of the cable.